1. FIELD OF THE INVENTION
This invention relates to a method of operating a gas recovery installation for a gas which is intermittently and/or irregularly released from a source, e.g. carbon monoxide-containing gas from an oxygen steel converter. The invention also relates to an apparatus for employing the method in the form of a steel converter having a gas recovery and distribution system
2. DESCRIPTION OF THE PRIOR ART
In the production of oxygen steel, liquid iron is brought into close contact with oxygen in a converter, in order to reduce the content of unwanted elements in the iron, especially carbon. During this production process, which is well known in the art, gas containing carbon monoxide, formed by carbon which is released from the liquid iron and reacts with the oxygen supplied, is produced.
In this specification an oxygen steel converter is to be understood to mean not only the standard L.D. converter, but also bottom blown variants of it, and combinations of top- and bottom-blown variants.
The nature of this process means that gas containing carbon monoxide is released irregularly. An installation with one converter, for example, produces gas for five to nine minutes after which the production of gas is very much reduced for forty to sixty minutes. In the case of an installation with two converters, the interval between the periods when most gas is released is between twenty and forty minutes. This gas containing carbon monoxide which is released has an important economic value which makes it viable not to flare this gas but to make use of it in user installations which can process it.
Because the user installations for this gas do not generally permit any wide variations in the gas supply, a gas holder from which gas can be supplied more regularly to consumption (user) installations is required. One problem with this, however, is that since the quantity of carbon monoxide-containing gas released may undergo a substantial change in the course of time, the capacity of the gas holder would have to be extremely high to accommodate this change fully. In practice the dimensions of the gas holder are subject to limitations which are determined mainly by investment costs, which are higher for larger gas holders.
One possible result of this is that if the average gas supply over a certain period of time is greater than the average consumption level of the consumption installations, the gas holder will fill and the gas recovered will have to be flared off. The economic value of this gas is therefore lost. If the average gas supply over a specific period of time is lower than the average consumption level, the gas holder cannot continue to supply sufficient gas to the consumption installation after a period of time. As a result they must be shut down, leading to production loss and stoppage costs.